Charles e



(No Modell.)-

' G,- 1;.-SGR1BNER-- LOCK SWITCH FOB, ELECTRIC SWITCHBOARDS.

.N0..'5o2, 769. Patented Aug. 8, 1893.

winni UNITED STA-TES 'PATENTff-Orrlca CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

Lock-SWITCH .FOR ELECTRIC swITcHBoARDs.

l SPECIFICATION forming part of Letters Patent No. 502,769, dated August 8, 1'893.

nppiicafiontidnoyenber19,1887.. semina l255.597. (remodel.)

To all whom t Magnan/cern:

Be it known thatl, CHARLES ESCRIBNER, a citizen of the United States, residing at Chi.- cago, in the county of Cook and State of Illinois, have invented acertain new and useful lmprovement in Lock- Switches for Electric Switchboards, (Case No. 144,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming apart of this speci- -cation.

My invention relates to lock switches for electric switchboards, and its object is to provide for locking the plug to the movable portion of the switch in such manner that, whenever a plug is withdrawn, the connections of the switching device will be restored to their normal condition.

My invention is designed primarily for multiple switchboard systems in which normally open test circuits are used, these test circuits being connected to ground when their lines are in use.

My invention will be described with reference to the test circuits shown in my Patent No. 305,021, of September 9, 1884, though itis evident that by slightmechanical changes it might be applied to any other system, as, for example, the system ofMilo G. Kellogg, Patent No. 308,315, of November 18, 1884, or the system of William S. Ford described in his Patent No. 357,821, of February 15, 1887.

I-Ieretofore the connecting plugs have been provided with springs which are slipped over a ball on the end of the switch lever or drawbar. No means being provided for locking the plug to the ball, strong springs have been necessary and though made with the greatest care, the plug frequently is pulled oft without moving the bar back so as to bring the conneetions of the switch to their normal/position.

My invention is illustrated in the accompanying drawings, in which- Figure 1 is a sectional view of two springjack switches of a telephone line and the test circuit wire connected'therewith. Figs. 2 and 3 are views showing a modified form of springjack.

Like parts are indicated by similar letters of reference in the different figures.

The telephone line a connects with the spring-jack b on the first board yandfthence with the spring-jack c on the next board and thence normally to ground. The spring-jack I have shown consists ofthe metallic socket d, the movable piece e .provided with a ring of insulating material fand the spring g. The piece h insulated from the socket of the switch, serves as a test piece, the test wire t' being connected with allthe test pieces h of the spring-jacks of linea. v

I need not describe the calling and clearing out apparatus. The test maybe made in the usual manner, by touching a plug having a telephone in its circuit, to the test piece h of the spring-jack of the linetested. If the test circuit is crossed with the telephone line at any other board, a click will beheard in the telephone. If the lineis free',the.test wire will be open and no clickwill be-h'eard in the telephone. At spring-jack ovsuch a cross is shown between the test piece and socket through the mediumy of the inserted plug. These circuits and the method of testing are 01d. .-1

My invention hereinrelates more particularly to the plug andthe movable piece e of the spring-jack and my invention is not limited to any system of circuits which is changed'by pushing in and drawing out the rod or movablepiece e. The headorball k is of such form that the plugor clasp may be slipped over the same readily and-,locked thereon so thatwhen` the plug is withdrawn the rod will be pulled out to itsl normal position, whereupon the plug will let go of the rod. My plug Z consists of the rubber handle through which the" lexibleconducting cord passes, being connected tothe stem or metallic portion of the plug in any well-known way. The tip of the plug is a clamp, the jaw m being attached to the stem bya spring n. The clamp is cut out to correspond to the shape of the ball or knob upon the rod.Y ,Inorder to make a connection the clamp is placed over the end of the movable piece and pushed back into the plug hole, as shown at. switch c in Fig. l. When thek plug istthus ',inserted, the piece e is forced back and the line a disconnected from spring g and connected through the plug with a iieXible cord o. Now on withdrawing the plug, the circuit changing piece e is drawn forward to the position shown in spring-jack b. The knob 7c thus projects so as to be easily grasped by the clamp. As this piece e might accidentally be pushed back out of reach, I preferably use somespring and catch device to hold the knob out, as shown in Figs. 2 and 3. The spring p serves to force the central pin q out, as shown in Fig. 2. On pressing against the knob r on the end of the pin, the spring p will be compressed and the detent s which is secured to the said pin, will be brought into engagement with the stop or catch t, as shown in Fig. 3. When, however, the plug is placed over the end of the pin and pressed back against the sleeve u, the detent will not be brought into engagement with its catch, but the whole circuit changing piece will be forced back and the telephone line will be connected with the flexible cord of the plug and cut off at the same time from the central ofce ground.

I do not limit my invention to the precise construction shown, since it is evident that the lock plug may be applied in different ways without departing from my invention. When used in the Ford system it is evident that the movable piece e would be attached to the rods and that the rods would be operated to change the circuit by simply pressing the plug into the socketand withdrawing it therefrom, and since the plug would be automatically locked and unlocked, as herein described, there would be no danger of the plug slipping ed without restoring the normal circuit.

W'hatever may be the form of my device,

the plug hole and the clamp of the plug and the movable piece must be so constructed that the plug, on being withdrawn, changes the position of the movable piece sufficiently to bring the circuits to their normal condition. The clamp thus remains locked to the circuit changing piece or rod until it is fully withdrawn from the plug hole and thereupon is unlocked.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. The combination with the clamp upon the plug, of the movable piece to which the clamp is fitted, and the plug socket from which the movable piece normally projects, said plug socket being adapted to receive the clamp and hold the same locked to the movable piece while the plug is being reciprocated within the socket, substantially as and for the purpose specified.

2. The combination with a plug socket, of a movable pin inserted therein, a spring which normally holds said pin extended, a detent which locks the pin in this normally extended position, and aconnecting plug provided with a clamp adapted to t over the pin to move the same, substantially as and for the purpose specified.

In witness whereof I hereunto subscribe my name this 17th day of October, A. D. 1887.

CHARLES E. SCRIBNER.

Witnesses:

GEORGE P. BARTON, W. M. CARPENTER, 

